Racing signal-interrupted connect() and sockmap update may result in an unconnected (and missing vsock transport) socket in a sockmap.
Test spends 2 seconds attempting to reach WARN_ON_ONCE().
connect / state = SS_CONNECTED / sock_map_update_elem if signal_pending state = SS_UNCONNECTED
connect transport = NULL vsock_bpf_recvmsg WARN_ON_ONCE(!vsk->transport)
Signed-off-by: Michal Luczaj mhal@rbox.co --- .../selftests/bpf/prog_tests/sockmap_basic.c | 111 +++++++++++++++++++++ 1 file changed, 111 insertions(+)
diff --git a/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c b/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c index 1e3e4392dcca0e1722c1982ecc649a80c27443b2..5c278353a924294a1452f650634cec0539804b1a 100644 --- a/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c +++ b/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c @@ -3,6 +3,7 @@ #include <error.h> #include <netinet/tcp.h> #include <sys/epoll.h> +#include <linux/time64.h>
#include "test_progs.h" #include "test_skmsg_load_helpers.skel.h" @@ -1042,6 +1043,114 @@ static void test_sockmap_vsock_unconnected(void) xclose(map); }
+#define CONNECT_SIGNAL_RACE_TIMEOUT 2 /* seconds */ + +static void sig_handler(int signum) +{ + /* nop */ +} + +static void connect_signal_racer_cleanup(void *map) +{ + xclose(*(int *)map); +} + +static void *connect_signal_racer(void *arg) +{ + int map; + + map = bpf_map_create(BPF_MAP_TYPE_SOCKMAP, NULL, sizeof(int), + sizeof(int), 1, NULL); + if (!ASSERT_OK_FD(map, "bpf_map_create")) + return NULL; + + pthread_cleanup_push(connect_signal_racer_cleanup, &map); + + for (;;) { + int c = *(int *)arg; + int zero = 0; + + (void)bpf_map_update_elem(map, &zero, &c, BPF_ANY); + + if (kill(0, SIGUSR1)) { + FAIL_ERRNO("kill"); + break; + } + + pthread_testcancel(); + } + + pthread_cleanup_pop(1); + + return NULL; +} + +static void test_sockmap_vsock_connect_signal_race(void) +{ + struct sockaddr_vm addr = { + .svm_family = AF_VSOCK, + .svm_cid = VMADDR_CID_LOCAL, + .svm_port = VMADDR_PORT_ANY + }; + struct sockaddr_vm bad_addr; + sighandler_t orig_handler; + pthread_t thread; + socklen_t alen; + int s, c, p; + __u64 tout; + + orig_handler = signal(SIGUSR1, sig_handler); + if (!ASSERT_NEQ(orig_handler, SIG_ERR, "signal handler setup")) + return; + + s = socket_loopback(AF_VSOCK, SOCK_SEQPACKET | SOCK_NONBLOCK); + if (s < 0) + goto restore; + + alen = sizeof(addr); + if (xgetsockname(s, (struct sockaddr *)&addr, &alen) < 0) + goto close; + + bad_addr = addr; + bad_addr.svm_cid = 0x42424242; /* non-existing */ + + if (xpthread_create(&thread, 0, connect_signal_racer, &c)) + goto close; + + tout = get_time_ns() + CONNECT_SIGNAL_RACE_TIMEOUT * NSEC_PER_SEC; + do { + c = xsocket(AF_VSOCK, SOCK_SEQPACKET, 0); + if (c < 0) + break; + + if (!connect(c, (struct sockaddr *)&addr, alen) || + errno != EINTR) + goto retry; + + if (!connect(c, (struct sockaddr *)&bad_addr, alen) || + errno != ESOCKTNOSUPPORT) + goto retry; + + if ((recv(c, &(char){0}, 1, MSG_DONTWAIT) < 0) && + errno == ENODEV) { + FAIL_ERRNO("recv"); + tout = 0; + } +retry: + xclose(c); + p = accept(s, NULL, NULL); + if (p >= 0) + xclose(p); + } while (get_time_ns() < tout); + + ASSERT_OK(pthread_cancel(thread), "pthread_cancel"); + xpthread_join(thread, NULL); +close: + xclose(s); +restore: + ASSERT_NEQ(signal(SIGUSR1, orig_handler), SIG_ERR, "handler restore"); +} + void test_sockmap_basic(void) { if (test__start_subtest("sockmap create_update_free")) @@ -1108,4 +1217,6 @@ void test_sockmap_basic(void) test_sockmap_skb_verdict_vsock_poll(); if (test__start_subtest("sockmap vsock unconnected")) test_sockmap_vsock_unconnected(); + if (test__start_subtest("sockmap vsock connect signal race")) + test_sockmap_vsock_connect_signal_race(); }